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// The .NET Foundation licenses this file to you under the MIT license.
// See the LICENSE file in the project root for more information
// 
// Licensed to the Apache Software Foundation (ASF) under one or more
// contributor license agreements. See the NOTICE file distributed with
// this work for additional information regarding copyright ownership.
// The ASF licenses this file to you under the Apache License, Version 2.0
// (the "License"); you may not use this file except in compliance with
// the License. You may obtain a copy of the License at
// 
// http://www.apache.org/licenses/LICENSE-2.0
// 
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// limitations under the License.
// 

using System;
using System.Collections;

using log4net.Core;

namespace log4net.Util
{
    /// <summary>Manages a mapping from levels to <see cref="LevelMappingEntry"/></summary>
    /// <remarks>
    /// <para>
    /// Manages an ordered mapping from <see cref="Level"/> instances 
    /// to <see cref="LevelMappingEntry"/> subclasses.
    /// </para>
    /// </remarks>
    /// <author>Nicko Cadell</author>
    public sealed class LevelMapping : IOptionHandler
    {
        /// <summary>Default constructor</summary>
        /// <remarks>
        /// <para>
        /// Initialise a new instance of <see cref="LevelMapping"/>.
        /// </para>
        /// </remarks>
        public LevelMapping() 
        {
        }

        /// <summary>Add a <see cref="LevelMappingEntry"/> to this mapping</summary>
        /// <param name="entry">the entry to add</param>
        /// <remarks>
        /// <para>
        /// If a <see cref="LevelMappingEntry"/> has previously been added
        /// for the same <see cref="Level"/> then that entry will be 
        /// overwritten.
        /// </para>
        /// </remarks>
        public void Add(LevelMappingEntry entry)
        {
            if (this.m_entriesMap.ContainsKey(entry.Level))
            {
                this.m_entriesMap.Remove(entry.Level);
            }

            this.m_entriesMap.Add(entry.Level, entry);
        }

        /// <summary>Lookup the mapping for the specified level</summary>
        /// <param name="level">the level to lookup</param>
        /// <returns>the <see cref="LevelMappingEntry"/> for the level or <c>null</c> if no mapping found</returns>
        /// <remarks>
        /// <para>
        /// Lookup the value for the specified level. Finds the nearest
        /// mapping value for the level that is equal to or less than the
        /// <paramref name="level"/> specified.
        /// </para>
        /// <para>
        /// If no mapping could be found then <c>null</c> is returned.
        /// </para>
        /// </remarks>
        public LevelMappingEntry Lookup(Level level)
        {
            if (this.m_entries != null)
            {
                foreach(LevelMappingEntry entry in this.m_entries)
                {
                    if (level >= entry.Level)
                    {
                        return entry;
                    }
                }
            }
            return null;
        }

        /// <summary>Initialize options</summary>
        /// <remarks>
        /// <para>
        /// Caches the sorted list of <see cref="LevelMappingEntry"/> in an array
        /// </para>
        /// </remarks>
        public void ActivateOptions()
        {
            Level[] sortKeys = new Level[this.m_entriesMap.Count];
            LevelMappingEntry[] sortValues = new LevelMappingEntry[this.m_entriesMap.Count];

            this.m_entriesMap.Keys.CopyTo(sortKeys, 0);
            this.m_entriesMap.Values.CopyTo(sortValues, 0);

            // Sort in level order
            Array.Sort(sortKeys, sortValues, 0, sortKeys.Length, null);

            // Reverse list so that highest level is first
            Array.Reverse(sortValues, 0, sortValues.Length);

            foreach(LevelMappingEntry entry in sortValues)
            {
                entry.ActivateOptions();
            }

            this.m_entries = sortValues;
        }

        private Hashtable m_entriesMap = new Hashtable();
        private LevelMappingEntry[] m_entries = null;
    }
}
